[GRASSLIST:6807] Re: cs2cs and grass

[Francesco Mirabella]

Many thanks to Paul and Tom, now I get and error of ~4cm due to the
original data error (4 decimal places in latlong data).

cheers,
Francesco


On Tue, May 17, 2005 at 02:57:35PM -0600, Tom Russo wrote:
> On Tue, May 17, 2005 at 07:20:19PM +0100, we recorded a bogon-computron collision of the <paul-grass at stjohnspoint.co.uk> flavor, containing:
> > Francesco Mirabella wrote:
> > [...]
> > >
> > >Just to check,
> > >I tried to project the point from WGS84 to Gauss Boaga using cs2cs:
> > >------------------------
> > > cs2cs -E +proj=latlong  +datum=WGS84 +to +proj=tmerc +lon_0=15
> > >  +k=0.9996 +x_0=2520000 +ellps=intl  -v -f %.6f
> > >------------------------
> > >
> > >
> > >After importing the point of check into the Gauss Boaga location, it
> > >results to be shifted about 167 m (mainly to the North) with respect to
> > >the point project (v.proj).
> > >
> > >where am I wrong? can anyone help??
> > 
> > Looks like you left +towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68 
> > out of the PROJ.4 description of the rome40 location, so the datum shift 
> > will not have happened there. Probably the GRASS result is the correct one?
> 
> Try using "g.proj -j" (print location projection in PROJ.4 format) in the 
> Gauss Boaga location and using the output of that for your cs2cs ... +to 
> options.  Bet it'll agree better, because then you can be sure you have all 
> the arguments that Grass is using.
> 
> -- 
> Tom Russo    KM5VY     SAR502  DM64ux         http://www.swcp.com/~russo/
> Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 
>  "The only thing you can do easily is be wrong, and that's hardly
>   worth the effort." -- Norton Juster

-- 
**********************************************
Francesco Mirabella,
Istituto Nazionale di Geofisica e Vulcanologia
Sismologia e Tettonofisica, Roma (Italy)
contact c/o:
Structural Geology and Geophysics
address: University of Perugia,
Dipartimento di Scienze della Terra
Piazza Universita', 1 06100 Perugia (Italy)
tel: ++39.(0)75.585 2651
fax: ++39.(0)75.585 2603
e-mail: mirabell at unipg.it
web: http://www.unipg.it/~mirabell/
**********************************************